1. Field of Invention
The invention relates generally to an alarm system for providing visual warnings and, more particularly, to a strobe alarm having a selectable strobe intensity.
2. Background of Invention
Signaling devices, such as strobe lights, are used to provide warning of potential hazards or to draw attention to an event or activity. An important field of use for these strobe lights is in electronic fire alarm systems. Strobe alarms typically include a flashtube and a trigger circuit for initiating firing of the flashtube. The energy for the flash is typically supplied from a capacitor connected in shunt with the flashtube. In some systems, the flash occurs when the voltage across the flash unit (i.e., the flashtube and associated trigger circuit) exceeds the threshold voltage required to actuate the trigger circuit, and in others the flash is triggered by a timing circuit. After the flashtube is triggered, it becomes conductive and rapidly discharges the stored energy from the shunt capacitor until the voltage across the flashtube has decreased to a value at which the flashtube is extinguished and becomes non-conductive.
As with most safety devices, the performance and installation of strobe alarms (including those strobe alarms equipped with an audio warning) are generally governed by federal, state and municipal regulations which require conformance to an Underwriters Laboratory (UL(copyright)) specification. For example, UL 1971 specifies that strobe alarms to have certain candela outputs when installed in various locations, e.g., ceilings, walls and the like. In order to comply with regulatory requirements, manufacturers offer strobe alarms in different candela intensities, e.g., 15, 30, 75 and 110 candela, in order to meet the full range regulatory intensity requirements.
Additionally, the intensity of the strobe alarm is required to be visible on the installed strobe alarms in a location accessible to an observer. Generally, this requirement is met by labeling the strobe alarm in a tamper-proof location. Alternately, a component, such as the reflector, is stamped or embossed to indicate the strobe intensity.
In order to meet these varied requirements, manufactures of strobe alarms have responded by producing multiple models of strobe alarms, each having a designated intensity. Since the intensity of each strobe alarm is controlled by a specific circuit configuration, a unique circuit board is normally utilized on each model. Additionally, the use of tamper-proof labeling wherein the components are embossed to indicate the candela output, prevents uses of those components on strobe alarms having intensities different than the embossed intensity value. Additionally, maintaining different production lines for the manufacture of strobe alarms having different predetermined candela intensities requires factory capacity to be apportioned among the each candela model. Furthermore, the stocking of components that are used in different models requires costly warehouse space and increases the likelihood of shipment errors.
Therefore, there is a need in the art for a strobe alarm that has a strobe intensity that is selectable from a predetermined range, i.e., a multi-candela strobe alarm. Such a strobe alarm should also comprise an indicator of the selected intensity that is visible to inspection while offering tamper-protection of the intensity setting.
The disadvantages associated with the prior art are overcome by the present invention of a strobe alarm that provides a selectable intensity setting. The inventive strobe alarm comprises a strobe assembly having a menu, a selector switch, and an actuator. The actuator engages the selector switch so that lateral movement of the actuator is translated to the selector switch. The actuator additionally points to the menu selection that corresponds to an intensity setting of the selector switch.
The actuator and the menu are positioned to readily denote the strobe intensity setting to an observer. The actuator is positioned within the strobe alarm so that it is easily adjusted upon installation but cannot be adjusted without removal of the housing, thus discouraging tampering.